First off, have lots of muscles... make sure you're as buff as they guys you're after. Two, make friends with them. Third, create an awkward situation where you're lathering up their body with hot oils and go from there. . .

At first I thought this said how to approach bodybuilders, period. There are a few at my gym and I want to talk to them for tips and such and am too shy around them and/or don't know what to say besides, "you're huge".

Ask them for tips on weight-lifting, let them correct you and then feed their ego. It takes time man, and eventually, you guys can be friendly, and also to be open in the conversation, casually comment, admit, or express interest in what you like: men. Then gauge their reaction. Being honest helps man, it does, but not too blunt, it's a game after all ;)